001/*
002 * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.replacements.nodes;
024
025import jdk.internal.jvmci.meta.*;
026
027import com.oracle.graal.graph.*;
028import com.oracle.graal.graph.spi.*;
029import com.oracle.graal.nodeinfo.*;
030import com.oracle.graal.nodes.CallTargetNode.InvokeKind;
031import com.oracle.graal.nodes.*;
032
033/**
034 * This node class can be used to create {@link MacroNode}s for simple pure functions like
035 * {@link System#identityHashCode(Object)}.
036 */
037@NodeInfo
038public abstract class PureFunctionMacroNode extends MacroStateSplitNode implements Canonicalizable {
039
040    public static final NodeClass<PureFunctionMacroNode> TYPE = NodeClass.create(PureFunctionMacroNode.class);
041
042    public PureFunctionMacroNode(NodeClass<? extends MacroNode> c, InvokeKind invokeKind, ResolvedJavaMethod targetMethod, int bci, JavaType returnType, ValueNode... arguments) {
043        super(c, invokeKind, targetMethod, bci, returnType, arguments);
044    }
045
046    /**
047     * This method should return either a constant that represents the result of the function, or
048     * null if no such result could be determined.
049     */
050    protected abstract JavaConstant evaluate(JavaConstant param, MetaAccessProvider metaAccess);
051
052    @Override
053    public Node canonical(CanonicalizerTool tool) {
054        if (tool.allUsagesAvailable() && hasNoUsages()) {
055            return null;
056        } else {
057            ValueNode param = arguments.get(0);
058            if (param.isConstant()) {
059                JavaConstant constant = evaluate(param.asJavaConstant(), tool.getMetaAccess());
060                if (constant != null) {
061                    return ConstantNode.forConstant(constant, tool.getMetaAccess());
062                }
063            }
064        }
065        return this;
066    }
067}